"Likely the trap is leaking. Best looked at from the ceiling of the
below you. If you think the leak is directly above where the stain is,
could just cut out a square foot of sheetrock around the dripping
see where the water is coming from. At that point you can decide if you
to bring in the condo repair guy. Your condo agreement may also limit
work you can do. "
I do repairs that I can myself too. But in this case, if the condo
will cover it, I would definitely go that route. And even if they
didn't, I would probably call in a plumber, because if it continued to
leak and/or damage occurred to property in the unit below from
repairing or from the leak not getting fixed the first time, etc, you
could have a claim against you.